These endings closely resemble the endings of der/die/das themselves. But there is a reason for this.

These are the endings that apply when nothing (i.e. no determiner) precedes the noun and thus you only have the adjective to indicate the gender, number and case, e.g. teurer Wein, frische Milch, kaltes Bier, gute Leute.

The full diversity of endings is needed here to convey these necessary grammatical relationships. But note that the masculine and neuter genitive endings are -en, not -es, which you would expect if this paradigm were exactly parallel to that of der/die/das (gen. des/der/des).

To emphasize this apparent discrepancy, the -en endings in the genitive, where -es might be expected, have had their n underlined in the paradigm above.

The ending -es in the genitive has been dispensed with here as the noun shows the case, because all masculine and neuter nouns end in -(e)s in the genitive singular (see 4.1), e.g. Anfang nächsten Monats (at the beginning of next month), Ende letzten Jahres (at the end of last year).

This is another example of the economy of the system of adjectival inl ection; two indicators of the genitive are considered superl uous in this instance.